The Sainsbury Laboratory, John Innes Centre, Colney, Norwich NR4 7UH, United Kingdom.
Proc Natl Acad Sci U S A. 2010 Oct 5;107(40):17421-6. doi: 10.1073/pnas.1008491107. Epub 2010 Sep 16.
Pathogens use specialized secretion systems and targeting signals to translocate effector proteins inside host cells, a process that is essential for promoting disease and parasitism. However, the amino acid sequences that determine host delivery of eukaryotic pathogen effectors remain mostly unknown. The Crinkler (CRN) proteins of oomycete plant pathogens, such as the Irish potato famine organism Phytophthora infestans, are modular proteins with predicted secretion signals and conserved N-terminal sequence motifs. Here, we provide direct evidence that CRN N termini mediate protein transport into plant cells. CRN host translocation requires a conserved motif that is present in all examined plant pathogenic oomycetes, including the phylogenetically divergent species Aphanomyces euteiches that does not form haustoria, specialized infection structures that have been implicated previously in delivery of effectors. Several distinct CRN C termini localized to plant nuclei and, in the case of CRN8, required nuclear accumulation to induce plant cell death. These results reveal a large family of ubiquitous oomycete effector proteins that target the host nucleus. Oomycetes appear to have acquired the ability to translocate effector proteins inside plant cells relatively early in their evolution and before the emergence of haustoria. Finally, this work further implicates the host nucleus as an important cellular compartment where the fate of plant-microbe interactions is determined.
病原体利用专门的分泌系统和靶向信号将效应蛋白转运到宿主细胞内，这一过程对于促进疾病和寄生至关重要。然而，决定真核病原体效应物向宿主输送的氨基酸序列在很大程度上仍然未知。卵菌植物病原体（如引起爱尔兰马铃薯饥荒的致病疫霉）的卷曲蛋白（CRN）是具有预测分泌信号和保守 N 端序列基序的模块化蛋白。在这里，我们提供了直接证据表明 CRN N 端介导蛋白向植物细胞的转运。CRN 宿主易位需要一个保守的基序，该基序存在于所有检查过的植物致病性卵菌中，包括系统发育上分化的物种无泡壶菌，它不形成吸器，专门的感染结构先前被认为参与了效应物的输送。几个不同的 CRN C 端定位于植物细胞核，并且在 CRN8 的情况下，需要核积累来诱导植物细胞死亡。这些结果揭示了一大类普遍存在的卵菌效应蛋白，它们以宿主核为靶标。卵菌似乎在进化的早期就获得了将效应蛋白转运到植物细胞内的能力，并且在吸器出现之前就获得了这种能力。最后，这项工作进一步暗示了宿主核作为一个重要的细胞区室，决定了植物-微生物相互作用的命运。
